[go: up one dir, main page]

WO1988004911A1 - Systeme d'amelioration d'electrocardiogrammes - Google Patents

Systeme d'amelioration d'electrocardiogrammes Download PDF

Info

Publication number
WO1988004911A1
WO1988004911A1 PCT/US1987/003476 US8703476W WO8804911A1 WO 1988004911 A1 WO1988004911 A1 WO 1988004911A1 US 8703476 W US8703476 W US 8703476W WO 8804911 A1 WO8804911 A1 WO 8804911A1
Authority
WO
WIPO (PCT)
Prior art keywords
frequency
signal
notches
frequency components
inter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1987/003476
Other languages
English (en)
Inventor
Lawrence Eisenberg
Michael A. Eisenberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SOUND ENHANCEMENT SYSTEMS Inc
Original Assignee
SOUND ENHANCEMENT SYSTEMS Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SOUND ENHANCEMENT SYSTEMS Inc filed Critical SOUND ENHANCEMENT SYSTEMS Inc
Publication of WO1988004911A1 publication Critical patent/WO1988004911A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/30—Input circuits therefor
    • A61B5/307—Input circuits therefor specially adapted for particular uses
    • A61B5/308—Input circuits therefor specially adapted for particular uses for electrocardiography [ECG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/30—Input circuits therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
    • A61B5/333—Recording apparatus specially adapted therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B7/00—Instruments for auscultation
    • A61B7/02—Stethoscopes
    • A61B7/04—Electric stethoscopes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7235—Details of waveform analysis
    • A61B5/7239—Details of waveform analysis using differentiation including higher order derivatives
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7235—Details of waveform analysis
    • A61B5/7253—Details of waveform analysis characterised by using transforms
    • A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S128/00—Surgery
    • Y10S128/92—Computer assisted medical diagnostics
    • Y10S128/925—Neural network

Definitions

  • the system of the present invention relates to the enhancement of electrocardiogram signals.
  • the system relates to the enhancement of small amplitude, high frequency notches and slurs which are difficult to record on conventional chart recorders and difficult to visually detect within an electrocardiogram waveform by medical personnel.
  • An electrocardiograph records electric potentials generated by the neuromuscular mechanism of the heart.
  • a stimulus arising in the sino-auricular node of the heart sets up a tiny electric current called the excitation or depolarization wave. This wave spreads over the auricular wall and the auricles contract.
  • the excitation wave is at the junctional tissue between auricle and ventricle, it is delayed by the atrioventricular node at the beginning of the. Bundle-of-His. The excitation wave conducts rapidly through the Bundle and then branches to the left and right ventricle.
  • the excitation wave then conducts slowly through the Purkinje fibers which terminate in the ventricular muscle, causing the ventricles to contract.
  • a period of heart rest follows, after which a fresh impulse arises at the sino-auricular node and the contraction cycle once again repeats.
  • This excitation waveform referred to as an electrocardiogram ( ⁇ CG)
  • ⁇ CG electrocardiogram
  • the electrocardiogram is divided up into five time segments, known to those skilled in the art as, P, Q, R, S, and T which correspond to the different parts of the waveform.
  • P, Q, R, S, and T correspond to the different parts of the waveform.
  • the "P” or Auricular Wave corresponds to the spread of the wave through the auricular musculature. At the point the wave spreads over the ventricular neural net of the Bundle-of-His, a rapid rise and fall of the wave potential, referred to as the "R" wave occurs.
  • the electrocardiogram Before the "R” wave portion, a small dip called the "Q” wave occurs in the electrocardiogram while after the "R” wave a large drop in the electrocardiogram occurs called the "S” wave.
  • the final portion of the electrocardiogram, the "T” wave corresponds to the resting phase of the ventricle during which time an electrical repolarization of the ventricular muscle occurs.
  • the electrocardiogram After the "T” wave the electrocardiogram reflects a horizontal line or isoelectric baseline indicating a period of heart rest prior to the next cycle of the excitation wave.
  • the electrocardiogram By analyzing deviations in the shape of the electrocardiogram, physicians can diagnose pathoiogical conditions which relate to the heart and circulatory system. Typically the electrocardiogram is recorded by a paper chart recorder and examined for deviations in the shape of the various segments of the waveform.
  • ECG signals are routed for display to a cathode-ray tube.
  • the display generated is then photographed to produce a permanent recording of the waveform.
  • This method is used in research facilities as a research tool and is not readily accessible to cardiologists, internists, and general practitioners outside this environment.
  • U.S. Patent 4,565,201 describes a signal averaging means which includes a microcomputer programmed to output information indicative of the ECG signal at a fraction of the speed of which it was input to the microcomputer.
  • a signal averaging means which includes a microcomputer programmed to output information indicative of the ECG signal at a fraction of the speed of which it was input to the microcomputer.
  • One method to overcome the problem of visual detection and analysis of the notches is to amplify the signal.
  • the amplitude of the notches is extremely small, (the ratio of the maximum amplitude of an ECG waveform to the maximum amplitude of a notch may be from 20:1 to 50:1) amplification of the entire waveform to increase the visibility of the notches would drive the signal off scale, saturating the display/recording device.
  • the signal is amplified to display the notches, the entire ECG waveform cannot be recorded by the chart recorder.
  • the notches occur quite frequently near the minimum and maximum amplitudes of the waveform, simultaneous recording of all the notches at the desired amplification is extremely difficult. It has been found that it is preferable that not only the notches, but the entire waveform and the positions of the notches with respect to the waveform be displayed/recorded for proper analysis and diagnosis.
  • U.S. Patent 3,809,071 describes a means to amplify and display low level signals without saturating the display/recording device. However in this method the larger amplitude signals which are amplified off the scale of the display/recording device are simply cut off at the point of saturation. Thus only the small amplitude signals are accurately displayed/recorded.
  • small amplitude, high frequency notches associated with myocardial disease and arrhythmias can be recorded by conventional chart recorders.
  • the notches are clearly visible in the recorded waveform for easy visual detection, inspection and analysis by medical personnel.
  • ECG signals having small amplitude, high frequency notches are automatically enhanced, first, by selectively amplifying the notches while keeping the amplitude of the remainder of the waveform constant and second, by uniformly expanding the signal in the time domain wherein the inter-component frequency and inter-component phase relationships of the signal are maintained. Because the enhancement system of the present invention automatically adjusts the enhancement parameters, the system is simplified and easy to use by medical personnel.
  • a Fast Fourier Transform is performed on the input signal to derive the frequency spectrum of the ECG signals.
  • the frequency components of the spectrum representing the notches are amplified and the entire frequency spectrum is translated into a lower frequency range.
  • the enhanced signal is subsequently transformed back into a time varying signal.
  • FIG. 1 is an illustration of the time varying waveform that comprises an electrocardiogram.
  • FIG. 2 displays an electrocardiogram where high frequency notches are present.
  • FIG . 3 ( a ) illustrates an unaltered time varying electrocardiogram signal as would be displayed on an Electrocardiograph chart recorder.
  • FIG. 3(b) shows the same electrocardiogram signal in which the frequency components representing the notches have been amplified relative to the rest of the signal.
  • FIG. 3(c) shows the electrocardiogram signal uniformly "expanded” in the time scale.
  • FIG. 4(a) illustrates the unaltered electrocardiogram signal in the frequency domain.
  • FIG. 4(b) shows the same signal after the amplitudes of the frequency components representing the notches have been amplified .
  • FIG. 4(c) shows the signal after time scale expansion.
  • FIG. 5 is a block diagram of an embodiment of the ECG enhancement system of the present invention.
  • FIGS. 6(a) and 6(b) is a flow diagram illustrating an embodiment of the electrocardiogram enhancement system of the present invention.
  • FIG. 7 is a block diagram of an apparatus for detecting and counting notches in the electrocardiogram waveform.
  • FIG. 8 is a flow diagram for a method of detecting and counting notches in the electrocardiogram waveform.
  • FIG. 1 shows the waveform of an electrocardiogram which comprises waveform segments "P" 10, “Q” 20, “R” 30, “S” 40, and “T” 50.
  • FIG. 2 shows the high frequency notches 60 that are common in the QRS complex in the case of coronary artery disease. These notches are characterized by small amplitude, rapid time variations that cannot be accurately reproduced by conventional chart recorders .
  • the high frequency notches In order for the ECG waveform to be useful for diagnostic analysis, the high frequency notches must be clearly visible within the waveform so that they can be inspected and analyzed by medical personnel. It is also necessary that the waveform be uniformly translated or expanded in the time domain, to a frequency range within the bandwidth of the chart recorder, in order that the original shape of the waveform (except for the amplified notches) can be accurately recorded on the chart recorder. In other words, each frequency and phase component of the waveform must be consistently modified in order to produce a translated waveform having a frequency range within the bandwidth of the chart recorder, in which the signal component amplitudes, inter-component frequency relationships and inter-component phase relationships among the integral signal components are maintained.
  • the original signal as illustrated in FIG. 3a
  • the original signal is automatically enhanced, first by selectively amplifying the notches 60 without affecting the rest of the waveform, as illustrated in FIG. 3b and, second, by uniformly expanding in the time domain the entire signal, as illustrated in FIG. 3c, in a manner that the high frequency notches 60 can be accurately reproduced by a chart recorder while maintaining the shape of the waveform.
  • the frequency spectrum of an ECG signal is approximated by calculating the discrete Fourier Transforms (DFT) of the waveform.
  • DFT discrete Fourier Transforms
  • FFT Fast Fourier Transform
  • the frequency spectrum of the input waveform signal is approximated by a series of points or frequency components at different discrete frequencies having amplitudes which correspond to the amplitudes of the input waveform signal at the respective discrete frequencies. Since a set of points defined by discrete frequency, amplitude and phase values result from performing the FFT operation, the sampled frequency spectrum signal obtained using the FFT operation is easily manipulated by performing mathematical operations on these values as discussed in detail below.
  • the notches which occur in the ECG waveform are very difficult to visually detect and analyze. Therefore it is desirable that these notches be selectively amplified with respect to the remainder of the waveform. In other words selective amplification permits only the notches to be amplified; the remainder of the waveform is not affected.
  • the amplitude of each frequency component within a predetermined frequency range and greater than a minimum amplitude value indicative of notches is multiplied by an amplification factor "H" .
  • the value of H is selected such that the amplification of the notches is sufficient for visual detection and analysis of the notches, but not too large that the recording device is saturated, that is, the limits of the device are not exceeded.
  • the value of H is determined by calculating the ratio of the largest amplitude of the frequency components representing the ECG signal, i.e. the "non-notch" frequency components, to the largest amplitude of the frequency components representing the notches, i.e. the notch frequency components, and multiplying the ratio by a gain factor "G" such that the notch is easily discernible without significantly changing the shape of the wave.
  • the value of H is determined by calculating the ratio of the largest amplitude of those frequency components up to and including 100 Hz to the largest amplitude of those frequency components greater than 100 Hz and multiplying the ratio by the gain factor G.
  • the gain factor G may be determined empirically based on the waveform.
  • G ranges from a value greater than zero up to one. Most preferably G is equal to 1/4.
  • the frequency range and minimum amplitude value are set such that only the frequency components representing the high frequency notches are amplified.
  • the frequency components representing a notch typically center around frequencies in the range of 600-1000 Hz, while the frequency components representing the remainder of the waveform are below 100 Hz. However, it has been found that the spectrum of frequency components representing a notch may range from 100 to 1500 Hz. Although the frequency components representing a notch may range from 100 to 1500 Hz, it is preferred that the frequency range is greater than 100Hz up to and including 1200 Hz, thereby accounting for the majority of notch frequency components.
  • the minimum amplitude is selected to exclude high frequency signal noise which can distort the signal. Preferably the minimum amplitude is approximately 5% of the peak amplitude of the notch frequency components, that is, the frequency components above 100 Hz.
  • the frequency spectrum representing the entire waveform is translated to a lower frequency range that is within the bandwidth of the chart recorder.
  • the frequency components are translated or shifted down by dividing the frequency of each of the frequency components by a time scale expansion factor, K.
  • K This time scale expansion factor is chosen so that the higher frequency components are translated down to lower frequencies within the bandwidth of the chart recorder while other lower frequency components that are also translated remain within the bandwidth of the chart recorder.
  • the translated frequency spectrum is subsequently transformed back into a time varying signal by performing an inverse FFT operation. Since the FFT components comprise both real and imaginary elements, thus taking into account both the frequency and phase elements of the signal, the operation of translating the frequency spectrum does not alter the inter-component phase and inter-component frequency relationships among the components in the spectrum. Therefore, except for the deliberate amplification of the notches, the expanded waveform in the time domain maintains its original shape.
  • the frequency components in the range greater than 100 Hz up to and including 1200 Hz represent notches.
  • a 1 the peak value of the non-notch frequency components
  • a 2 the peak value of the notch frequency components have values of 200 mv and 10 mv respectively.
  • the frequency components representing the notches in Fig. 4a are increased in amplitude by a factor of 5, as shown in FIG. 4b.
  • the frequency spectrum illustrated in Figs. 4b is then translated or expanded in the time scale by a factor of 10 as illustrated in FIG. 4c.
  • the 1000 Hz frequency component in FIG. 4b has been translated so that it is now at 100 Hz in FIG. 4c.
  • the frequencies of the remaining components in the signal shown in FIG. 4b are all divided by the time scale expansion factor resulting in the frequency spectrum illustrated in FIG. 4c.
  • the time scale expansion factor K used to obtain the frequency spectrum of FIG. 4c from that shown in FIG. 4b is equal to 10, this value for K is only used as an example and other values for K can be used.
  • the inter-component phase and inter-component frequency relationshhips remain equivalent. As shown in FIG. 4b, the 50 Hz and 100 Hz components are separated by one octave. In FIG. 4c, the respective translated frequency components, at 5 Hz and 10 Hz, are also separated by one octave. Thus, the inter-component frequency and inter- component phase relationships in the signal are maintained in the enhanced signal after the entire frequency spectrum of the signal is translated into a range suitable for accurate reproduction of the signal on a conventional chart recorder.
  • FIG. 5 is a schematic diagram of an embodiment of the ECG enhancement system of the present invention in which an electrical signal generated by the heart is detected, amplified and input to a microprocessor. There the frequency components representing the notches are selectively amplified and the time scale of the entire signal is then uniformly expanded or translated so that the processed signal can be reproduced accurately on a conventional chart recorder.
  • a series of electrodes are placed on the surface of the chest of the patient.
  • the potential generated by heart contractions is then measured between a selected pair of electrodes.
  • the measured signal 85 is amplified by amplifier 90 so that the entire signal comprising the electrocardiogram is amplified for processing.
  • the amplified signal is then preferably passed through a 60 Hz filter 100 to remove any interference typically at 60 Hz in the signal due to the surrounding environment.
  • the signal is then input to a microprocessor 110 where a Fourier Transform of the signal is generated, the frequency components representing the notches are selectively amplified, the time scale of the entire frequency spectrum of the signal is uniformly expanded and an inverse Fourier Transform is performed to output a time varying signal.
  • the signal output is sent to a chart recorder 120 for accurate reproduction of the enhanced ECG signal.
  • the microprocessor 110 performs a number of mathematical operations on the ECG signal to selectively enhance the amplitude of the frequency components representing notches and to uniformly expand the ECG waveform in the time scale.
  • the operations that the microprocessor 110 performs are analog to digital conversion of the signal, signal sampling, Fourier transform, amplification of the amplitudes of the frequency components representing the notches, time scale expansion, inverse Fourier transform, digital to analog conversion, and storage of the information in temporary and permanent memory.
  • analog to digital and digital to analog signal conversion can be performed external to the microprocessor.
  • the microprocessor 110 is a CMOS microprocessor such as the 8 bit MC68HC11A4 microprocessor manufactured by Motorola Inc. of Schaumburg, Illinois, although other devices with similar capabilities can be used.
  • FIGS. 6a and 6b together show a flow diagram describing the operation of the microprocessor of the embodiment of the present invention illustrated in FIG. 5.
  • the amplified ECG signal is received by the microprocessor and converted from an analog signal to a digital signal in block 131.
  • the start of the ECG waveform is determined. Preferably the beginning of this waveform is determined automatically.
  • a peak detector is used to determine the maximum amplitude of the ECG waveform which occurs at the peak of the "R " wave .
  • the threshold level of a threshold detector is then set an arbitrary amount below this maximum amplitude.
  • a pulse is generated which triggers a time delay having a duration approximately equal to the expected time period between heart pulses.
  • the duration of the time delay is about 750 milliseconds. The time delay is used to inhibit the operation of the threshold detector until the beginning of the next heart pulse.
  • the duration of the delay is automatically adjusted to accommodate different pulse rates by setting the time delay to a duration less than the pulse rate.
  • the time delay generator and threshold detector are synchronized to insure operation at the appropriate times such that every time another ECG waveform is detected, another trigger pulse is automatically generated.
  • a counter is used to count the number of ECG waveforms for sampling.
  • N a predetermined number "N" of ECG waveforms, corresponding to the number of trigger pulses generated by exceeding the threshold of the threshold detector, have been detected by the ECG waveform counter. If N pulses have not been detected, in block 138 it is determined whether the input electrical signal was sampled (in block 140) within the last dT seconds. If the previous ECG waveform sampling occurred within the last dT seconds, the sampling of the waveform is delayed a fixed period of time as shown by block 142. If the previous ECG waveform sampling occurred more than dT seconds previously, the input electrical signal is sampled as shown by block 140 and the amplitudes of the stored waveform are stored in the memory portion of the microprocessor.
  • the input electrical signal comprising the N ECG waveforms is sampled every dT seconds and a sampled input signal is obtained.
  • dT is equal to 20 microseconds although other values for dT can be chosen.
  • the microprocessor initiates the process again and re-determines in block 136 whether N waveforms have been detected.
  • a signal corresponding to the frequency spectrum of these sampled waveforms is obtained, by calculating the fast Fourier transform (FFT) of the waveform, in block 144 as shown in FIG. 6b and is stored in the memory of the microprocessor.
  • FFT fast Fourier transform
  • Block 145 all components of the frequency spectrum which lie in the range greater than 100 up to and including 1200 Hz are examined.
  • the frequency components in this range which are greater than 5% of the peak amplitude of the notch frequency components are typically representative of notches.
  • the amplification factor H is automatically calculated by the microprocessor to be equal to the ratio of the peak amplitude of the non-notch frequency components to the peak amplitude of the frequency components multiplied by the gain factor G.
  • the selected frequency components are multiplied by the amplification factor H, as shown in Block 147.
  • the signal may be translated or expanded on the time scale if each discrete FFT frequency value or component is divided by the time scale expansion factor K.
  • This time scale expansion factor is chosen so that the most rapid time variations of the ECG waveform (the notches) will be slowed down to the point that a chart recorder pen can accurately follow and reproduce the waveform.
  • the time scale expansion factor may be calculated for a particular waveform or a fixed time scale expansion factor may be used.
  • the highest frequency value of the waveform is obtained and the time scale expansion factor is calculated in block 150 by determining the value which will bring the highest frequency component into the bandwidth of the chart recorder.
  • each frequency component of the sampled frequency spectrum is divided by the time scale expansion factor K.
  • a time varying output electrical signal is obtained from the translated frequency spectrum in block 154 by performing an inverse FFT operation on the signal.
  • the enhanced time varying signal is optionally repeated a number of times as shown in box 156, repeat output.
  • the signal is then converted from a digital to analog signal and sent to the ECG recorder for subsequent recording of the signal.
  • microprocessor 110 can be described mathematically. If the original time varying input signal is f(t) , its frequency spectrum as shown in FIG. 4a is F( ⁇ ) and the amplified frequency spectrum is F' ( ⁇ ) then
  • K is the time scale expansion factor
  • the resulting time varying output signal is equivalent to the time varying input signal expanded in time by a factor of K.
  • the output wave f has the exact shape of f(t) except for the time scale expansion. It follows with respect to the high frequency notches that the enhanced signal f' (t) is equal to Hf' (t/K) and the remainder of the waveform is equal to f'(t/K).
  • FIG. 7 Another embodiment of the present invention, is illustrated in FIG. 7.
  • the electrical signal generated by the heart is measured at 85, and amplified by amplifier 90.
  • the signal is then preferably passed through a 60 Hz filter 100 to remove any interference typically at 60 Hz in the signal due to the surrounding environment.
  • the signal is subsequently input to microprocessor 110.
  • the signal is converted from an analog to digital signal, a Fourier transform of the signal is generated, the frequency components representing the notches are amplified, the time scale of the entire frequency spectrum of the signal is uniformly expanded and an inverse Fourier transform and digital-to-analog conversion are performed to output a time varying signal to be output to the chart recorder 120 for accurate recording of the signal.
  • an inverse Fourier transform of the notch portion of the signal is generated and output to a threshold detector 122 for the detection of those notches of a predetermined minimum amplitude.
  • the output pulse of the threshold detector 122 is counted by a digital counter 123 and output to a numeric display 124.
  • digital techniques involving the determination of the first derivative of the signal waveform and the count of the number of zero crossings of the first derivative that occur within a certain time span can be used to detect notches.
  • the beginning of the QRS wave is first detected in block 212 and the minima, maxima and notch counters are initialized in block 213.
  • the slopes at a predetermined time t i and t i+1 are calculated in blocks 214, 215 and compared in block 216. A change in the sign of the slope indicates a zero crossing in block 217.
  • the next test of the signal is taken at block 218 and the slopes calculated and compared with the last slope value. If the sign of the slopes at t i and t i+1 are not the same and the slope at t i+1 is less than zero, the maxima counter is incremented by one in block 222 and the notch counter is incremented by one in block 221. If the slope at t i+1 is greater than or equal to zero, the minima counter in block 219 as well as the notch counter in block 221 are incremented by one.
  • T i and the slope at t i are set equal to t i+1 and the slope at t i+1 respectively in block 220.
  • the slope at the next test point is then calculated and compared. This process continues until the end of the QRS wave is detected in block 217.
  • the notch, minima, and maxima counts are used by physicians to analyze coronary artery disease and arrhythmia.
  • the time between tests for determining the first derivative of the signal i.e., the difference in time between t i and t i+1 is a fixed amount of time which is preferably determined empirically.
  • An illustrative frequency is 800 Hz.
  • the sampling rate of the signal used in one embodiment of the present invention must be equal to the testing rate for determination of the first derivative.
  • the signal may be sampled at a rate of 5000 Hz and tested for the derivative of the signal at a rate of 1000 Hz.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Animal Behavior & Ethology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Veterinary Medicine (AREA)
  • Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Acoustics & Sound (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Cardiology (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)

Abstract

Des signaux d'électrocardiogramme (85) de faible amplitude et à flancs raides à haute fréquence sont améliorés d'abord par une amplification sélective des flancs raides (110), l'amplitude du reste de l'onde étant maintenue constante, et ensuite par l'expansion uniforme du signal (110) dans le domaine de temps où les relations de fréquence intercomposantes et de phase intercomposantes sont préservées. Ces signaux sont appliqués à un enregistreur de diagrammes pour électrocardiogrammes (120).
PCT/US1987/003476 1986-12-31 1987-12-31 Systeme d'amelioration d'electrocardiogrammes Ceased WO1988004911A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/948,195 US4862897A (en) 1985-11-05 1986-12-31 Electrocardiogram enhancement system and method
US948,195 1992-09-21

Publications (1)

Publication Number Publication Date
WO1988004911A1 true WO1988004911A1 (fr) 1988-07-14

Family

ID=25487457

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1987/003476 Ceased WO1988004911A1 (fr) 1986-12-31 1987-12-31 Systeme d'amelioration d'electrocardiogrammes

Country Status (3)

Country Link
US (1) US4862897A (fr)
AU (1) AU1157088A (fr)
WO (1) WO1988004911A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11240579B2 (en) 2020-05-08 2022-02-01 Level 42 Ai Sensor systems and methods for characterizing health conditions

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4960129A (en) * 1988-12-05 1990-10-02 Trustees Of The University Of Pennsylvania Methods of observing autonomic neural stimulation and diagnosing cardiac dynamical dysfunction using heartbeat interval data to analyze cardioventilatory interactions
US5046504A (en) * 1989-02-01 1991-09-10 Corazonix Corporation Method and apparatus for analyzing and interpreting electrocardiograms using spectro-temporal mapping
US5012815A (en) * 1989-02-02 1991-05-07 Yale University Dynamic spectral phonocardiograph
US5039937A (en) * 1990-05-11 1991-08-13 Nicolet Instrument Corporation Method and apparatus for providing compressed and expanded displays on a digital oscilloscope
US5263486A (en) * 1991-11-01 1993-11-23 Telectronics Pacing Systems, Inc. Apparatus and method for electrocardiogram data compression
AU1837495A (en) 1994-10-13 1996-05-06 Horus Therapeutics, Inc. Computer assisted methods for diagnosing diseases
US6050950A (en) 1996-12-18 2000-04-18 Aurora Holdings, Llc Passive/non-invasive systemic and pulmonary blood pressure measurement
US6278890B1 (en) 1998-11-09 2001-08-21 Medacoustics, Inc. Non-invasive turbulent blood flow imaging system
US6193668B1 (en) 1997-11-10 2001-02-27 Medacoustics, Inc. Acoustic sensor array for non-invasive detection of coronary artery disease
US6261237B1 (en) 1998-08-20 2001-07-17 Medacoustics, Inc. Thin film piezoelectric polymer sensor
WO2003079891A2 (fr) 2002-03-18 2003-10-02 Sonomedica, Llc Procede et systeme permettant de generer un coefficient de vraisemblance pour une maladie cardio-vasculaire, d'analyser des signaux sonores cardio-vasculaires a distance a partir de l'emplacement d'acquisition des signaux sonores cardio-vasculaires, et de determiner des informations de temps et de phase a partir des signaux
US20070117075A1 (en) * 2005-11-22 2007-05-24 Gordon Michael S Cardiopulmonary patient simulator
US20070117076A1 (en) * 2005-11-22 2007-05-24 Gordon Michael S Cardiopulmonary patient simulator
US7316568B2 (en) * 2005-11-22 2008-01-08 University Of Miami Cardiopulmonary patient simulator
US8363048B2 (en) * 2006-11-16 2013-01-29 General Electric Company Methods and apparatus for visualizing data
EP2846684B1 (fr) 2012-05-09 2021-11-03 CardioInsight Technologies, Inc. Détection d'intégrité de canal
US11284827B2 (en) 2017-10-21 2022-03-29 Ausculsciences, Inc. Medical decision support system
US10874318B2 (en) 2018-03-06 2020-12-29 Cardioinsight Technologies, Inc. Channel integrity detection and reconstruction of electrophysiological signals

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4534361A (en) * 1981-11-02 1985-08-13 Robert Bosch Gmbh Method and apparatus for measuring blood pressure by instantaneous comparison of multiple frequency-range components of Korotkoff noise
US4594731A (en) * 1984-11-09 1986-06-10 University Of Utah Electronic stethoscope

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3267934A (en) * 1962-09-20 1966-08-23 Avionics Res Products Corp Electrocardiac computer
DE2333275A1 (de) * 1972-06-30 1974-01-24 Olympus Optical Co Geraet zur aufzeichnung und/oder wiedergabe biologischer vorgaenge
US3859556A (en) * 1972-11-15 1975-01-07 Nicolet Instrument Corp Digital measurement apparatus with improved expanded display
FR2425231A1 (fr) * 1978-05-12 1979-12-07 Cm Ind Procede et dispositif de traitement et de visualisation d'un signal de lecture d'un enregistrement d'electrocardiogramme lu a une vitesse superieure a la vitesse d'enregistrement
US4367753A (en) * 1980-01-23 1983-01-11 Medtronic Inc. Apparatus for monitoring and storing heartbeats of a patient
US4506677A (en) * 1982-12-21 1985-03-26 Honeywell Inc. Indicating device for defibrillators
US4509526A (en) * 1983-02-08 1985-04-09 Lawrence Medical Systems, Inc. Method and system for non-invasive ultrasound Doppler cardiac output measurement
US4483346A (en) * 1983-08-25 1984-11-20 Intech Systems Corp. Electrocardiograph with digitally-printing waveform display
US4606352A (en) * 1984-07-13 1986-08-19 Purdue Research Foundation Personal electrocardiogram monitor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4534361A (en) * 1981-11-02 1985-08-13 Robert Bosch Gmbh Method and apparatus for measuring blood pressure by instantaneous comparison of multiple frequency-range components of Korotkoff noise
US4594731A (en) * 1984-11-09 1986-06-10 University Of Utah Electronic stethoscope

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11240579B2 (en) 2020-05-08 2022-02-01 Level 42 Ai Sensor systems and methods for characterizing health conditions
US12483815B2 (en) 2020-05-08 2025-11-25 Level 42 Ai Sensor systems and methods for characterizing health conditions

Also Published As

Publication number Publication date
AU1157088A (en) 1988-07-27
US4862897A (en) 1989-09-05

Similar Documents

Publication Publication Date Title
US4862897A (en) Electrocardiogram enhancement system and method
US4428380A (en) Method and improved apparatus for analyzing activity
US4628939A (en) Method and improved apparatus for analyzing heart activity
US4136690A (en) Method and apparatus for vector analysis of ECG arrhythmias
US5404880A (en) Scatter diagram analysis system and method for discriminating ventricular tachyarrhythmias
US5758654A (en) ECG P QRS T onset and peak detection method
US7383079B2 (en) Nonlinear method and apparatus for electrocardiogram pacemaker signal filtering
US6161037A (en) Methods and apparatus for R-wave detection
EP0552009A1 (fr) Analyseur d'électrocardiogrammes
US5954666A (en) System for analyzing specific portions of cardiac waveforms
US3878832A (en) Method and apparatus for detecting and quantifying cardiovascular murmurs and the like
WO1993004627A1 (fr) Procedes de cardiographie par impedance et de determination du rythme cardiaque
JPS5937107B2 (ja) 心電計コンピユ−タ
Dalle et al. Computer analysis of bowel sounds
US6668189B2 (en) Method and system for measuring T-wave alternans by alignment of alternating median beats to a cubic spline
JPH0852117A (ja) 患者モニタ
US3822696A (en) Electrocardiography st analyzer and method
Saad et al. Detection of heart blocks in ECG signals by spectrum and time-frequency analysis
Denniss et al. Technique for maximizing the frequency response of the signal averaged Frank vectorcardiogram
Kabari et al. Bradycardia detection using ECG signal processing and matlab
JP3198451B2 (ja) 雑音除去方法及び装置
US6238350B1 (en) Method of analyzing a cardiac signal
Burke et al. ECG analysis using the Mexican-Hat wavelet
Patel et al. Evaluating ECG capturing using sound-card of PC/laptop
Van Den Akker et al. An on-line method for reliable detection of waveforms and subsequent estimation of events in physiological signals

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU JP KR

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE FR GB IT LU NL SE

WWE Wipo information: entry into national phase

Ref document number: 1988900941

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1988900941

Country of ref document: EP